fs/proc/kcore.c

   1 /*
   2  *      fs/proc/kcore.c kernel ELF core dumper
   3  *
   4  *      Modelled on fs/exec.c:aout_core_dump()
   5  *      Jeremy Fitzhardinge <jeremy@sw.oz.au>
   6  *      ELF version written by David Howells <David.Howells@nexor.co.uk>
   7  *      Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
   8  *      Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
   9  *      Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
  10  */
  11
  12 #include <linux/mm.h>
  13 #include <linux/proc_fs.h>
  14 #include <linux/user.h>
  15 #include <linux/capability.h>
  16 #include <linux/elf.h>
  17 #include <linux/elfcore.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/highmem.h>
  20 #include <linux/bootmem.h>
  21 #include <linux/init.h>
  22 #include <linux/slab.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/io.h>
  25 #include <linux/list.h>
  26 #include <linux/ioport.h>
  27 #include <linux/memory.h>
  28 #include <asm/sections.h>
  29
  30 #define CORE_STR "CORE"
  31
  32 #ifndef ELF_CORE_EFLAGS
  33 #define ELF_CORE_EFLAGS 0
  34 #endif
  35
  36 static struct proc_dir_entry *proc_root_kcore;
  37
  38
  39 #ifndef kc_vaddr_to_offset
  40 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
  41 #endif
  42 #ifndef kc_offset_to_vaddr
  43 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
  44 #endif
  45
  46 /* An ELF note in memory */
  47 struct memelfnote
  48 {
  49         const char *name;
  50         int type;
  51         unsigned int datasz;
  52         void *data;
  53 };
  54
  55 static LIST_HEAD(kclist_head);
  56 static DEFINE_RWLOCK(kclist_lock);
  57 static int kcore_need_update = 1;
  58
  59 void
  60 kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
  61 {
  62         new->addr = (unsigned long)addr;
  63         new->size = size;
  64         new->type = type;
  65
  66         write_lock(&kclist_lock);
  67         list_add_tail(&new->list, &kclist_head);
  68         write_unlock(&kclist_lock);
  69 }
  70
  71 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
  72 {
  73         size_t try, size;
  74         struct kcore_list *m;
  75
  76         *nphdr = 1; /* PT_NOTE */
  77         size = 0;
  78
  79         list_for_each_entry(m, &kclist_head, list) {
  80                 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
  81                 if (try > size)
  82                         size = try;
  83                 *nphdr = *nphdr + 1;
  84         }
  85         *elf_buflen =   sizeof(struct elfhdr) +
  86                         (*nphdr + 2)*sizeof(struct elf_phdr) +
  87                         3 * ((sizeof(struct elf_note)) +
  88                              roundup(sizeof(CORE_STR), 4)) +
  89                         roundup(sizeof(struct elf_prstatus), 4) +
  90                         roundup(sizeof(struct elf_prpsinfo), 4) +
  91                         roundup(sizeof(struct task_struct), 4);
  92         *elf_buflen = PAGE_ALIGN(*elf_buflen);
  93         return size + *elf_buflen;
  94 }
  95
  96 static void free_kclist_ents(struct list_head *head)
  97 {
  98         struct kcore_list *tmp, *pos;
  99
 100         list_for_each_entry_safe(pos, tmp, head, list) {
 101                 list_del(&pos->list);
 102                 kfree(pos);
 103         }
 104 }
 105 /*
 106  * Replace all KCORE_RAM/KCORE_VMEMMAP information with passed list.
 107  */
 108 static void __kcore_update_ram(struct list_head *list)
 109 {
 110         int nphdr;
 111         size_t size;
 112         struct kcore_list *tmp, *pos;
 113         LIST_HEAD(garbage);
 114
 115         write_lock(&kclist_lock);
 116         if (kcore_need_update) {
 117                 list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
 118                         if (pos->type == KCORE_RAM
 119                                 || pos->type == KCORE_VMEMMAP)
 120                                 list_move(&pos->list, &garbage);
 121                 }
 122                 list_splice_tail(list, &kclist_head);
 123         } else
 124                 list_splice(list, &garbage);
 125         kcore_need_update = 0;
 126         proc_root_kcore->size = get_kcore_size(&nphdr, &size);
 127         write_unlock(&kclist_lock);
 128
 129         free_kclist_ents(&garbage);
 130 }
 131
 132
 133 #ifdef CONFIG_HIGHMEM
 134 /*
 135  * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
 136  * because memory hole is not as big as !HIGHMEM case.
 137  * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
 138  */
 139 static int kcore_update_ram(void)
 140 {
 141         LIST_HEAD(head);
 142         struct kcore_list *ent;
 143         int ret = 0;
 144
 145         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
 146         if (!ent)
 147                 return -ENOMEM;
 148         ent->addr = (unsigned long)__va(0);
 149         ent->size = max_low_pfn << PAGE_SHIFT;
 150         ent->type = KCORE_RAM;
 151         list_add(&ent->list, &head);
 152         __kcore_update_ram(&head);
 153         return ret;
 154 }
 155
 156 #else /* !CONFIG_HIGHMEM */
 157
 158 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 159 /* calculate vmemmap's address from given system ram pfn and register it */
 160 int get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 161 {
 162         unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
 163         unsigned long nr_pages = ent->size >> PAGE_SHIFT;
 164         unsigned long start, end;
 165         struct kcore_list *vmm, *tmp;
 166
 167
 168         start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
 169         end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
 170         end = ALIGN(end, PAGE_SIZE);
 171         /* overlap check (because we have to align page */
 172         list_for_each_entry(tmp, head, list) {
 173                 if (tmp->type != KCORE_VMEMMAP)
 174                         continue;
 175                 if (start < tmp->addr + tmp->size)
 176                         if (end > tmp->addr)
 177                                 end = tmp->addr;
 178         }
 179         if (start < end) {
 180                 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
 181                 if (!vmm)
 182                         return 0;
 183                 vmm->addr = start;
 184                 vmm->size = end - start;
 185                 vmm->type = KCORE_VMEMMAP;
 186                 list_add_tail(&vmm->list, head);
 187         }
 188         return 1;
 189
 190 }
 191 #else
 192 int get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 193 {
 194         return 1;
 195 }
 196
 197 #endif
 198
 199 static int
 200 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
 201 {
 202         struct list_head *head = (struct list_head *)arg;
 203         struct kcore_list *ent;
 204
 205         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
 206         if (!ent)
 207                 return -ENOMEM;
 208         ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT));
 209         ent->size = nr_pages << PAGE_SHIFT;
 210
 211         /* Sanity check: Can happen in 32bit arch...maybe */
 212         if (ent->addr < (unsigned long) __va(0))
 213                 goto free_out;
 214
 215         /* cut not-mapped area. ....from ppc-32 code. */
 216         if (ULONG_MAX - ent->addr < ent->size)
 217                 ent->size = ULONG_MAX - ent->addr;
 218
 219         /* cut when vmalloc() area is higher than direct-map area */
 220         if (VMALLOC_START > (unsigned long)__va(0)) {
 221                 if (ent->addr > VMALLOC_START)
 222                         goto free_out;
 223                 if (VMALLOC_START - ent->addr < ent->size)
 224                         ent->size = VMALLOC_START - ent->addr;
 225         }
 226
 227         ent->type = KCORE_RAM;
 228         list_add_tail(&ent->list, head);
 229
 230         if (!get_sparsemem_vmemmap_info(ent, head)) {
 231                 list_del(&ent->list);
 232                 goto free_out;
 233         }
 234
 235         return 0;
 236 free_out:
 237         kfree(ent);
 238         return 1;
 239 }
 240
 241 static int kcore_update_ram(void)
 242 {
 243         int nid, ret;
 244         unsigned long end_pfn;
 245         LIST_HEAD(head);
 246
 247         /* Not inialized....update now */
 248         /* find out "max pfn" */
 249         end_pfn = 0;
 250         for_each_node_state(nid, N_HIGH_MEMORY) {
 251                 unsigned long node_end;
 252                 node_end  = NODE_DATA(nid)->node_start_pfn +
 253                         NODE_DATA(nid)->node_spanned_pages;
 254                 if (end_pfn < node_end)
 255                         end_pfn = node_end;
 256         }
 257         /* scan 0 to max_pfn */
 258         ret = walk_system_ram_range(0, end_pfn, &head, kclist_add_private);
 259         if (ret) {
 260                 free_kclist_ents(&head);
 261                 return -ENOMEM;
 262         }
 263         __kcore_update_ram(&head);
 264         return ret;
 265 }
 266 #endif /* CONFIG_HIGHMEM */
 267
 268 /*****************************************************************************/
 269 /*
 270  * determine size of ELF note
 271  */
 272 static int notesize(struct memelfnote *en)
 273 {
 274         int sz;
 275
 276         sz = sizeof(struct elf_note);
 277         sz += roundup((strlen(en->name) + 1), 4);
 278         sz += roundup(en->datasz, 4);
 279
 280         return sz;
 281 } /* end notesize() */
 282
 283 /*****************************************************************************/
 284 /*
 285  * store a note in the header buffer
 286  */
 287 static char *storenote(struct memelfnote *men, char *bufp)
 288 {
 289         struct elf_note en;
 290
 291 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 292
 293         en.n_namesz = strlen(men->name) + 1;
 294         en.n_descsz = men->datasz;
 295         en.n_type = men->type;
 296
 297         DUMP_WRITE(&en, sizeof(en));
 298         DUMP_WRITE(men->name, en.n_namesz);
 299
 300         /* XXX - cast from long long to long to avoid need for libgcc.a */
 301         bufp = (char*) roundup((unsigned long)bufp,4);
 302         DUMP_WRITE(men->data, men->datasz);
 303         bufp = (char*) roundup((unsigned long)bufp,4);
 304
 305 #undef DUMP_WRITE
 306
 307         return bufp;
 308 } /* end storenote() */
 309
 310 /*
 311  * store an ELF coredump header in the supplied buffer
 312  * nphdr is the number of elf_phdr to insert
 313  */
 314 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 315 {
 316         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 317         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 318         struct elf_phdr *nhdr, *phdr;
 319         struct elfhdr *elf;
 320         struct memelfnote notes[3];
 321         off_t offset = 0;
 322         struct kcore_list *m;
 323
 324         /* setup ELF header */
 325         elf = (struct elfhdr *) bufp;
 326         bufp += sizeof(struct elfhdr);
 327         offset += sizeof(struct elfhdr);
 328         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 329         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 330         elf->e_ident[EI_DATA]   = ELF_DATA;
 331         elf->e_ident[EI_VERSION]= EV_CURRENT;
 332         elf->e_ident[EI_OSABI] = ELF_OSABI;
 333         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 334         elf->e_type     = ET_CORE;
 335         elf->e_machine  = ELF_ARCH;
 336         elf->e_version  = EV_CURRENT;
 337         elf->e_entry    = 0;
 338         elf->e_phoff    = sizeof(struct elfhdr);
 339         elf->e_shoff    = 0;
 340         elf->e_flags    = ELF_CORE_EFLAGS;
 341         elf->e_ehsize   = sizeof(struct elfhdr);
 342         elf->e_phentsize= sizeof(struct elf_phdr);
 343         elf->e_phnum    = nphdr;
 344         elf->e_shentsize= 0;
 345         elf->e_shnum    = 0;
 346         elf->e_shstrndx = 0;
 347
 348         /* setup ELF PT_NOTE program header */
 349         nhdr = (struct elf_phdr *) bufp;
 350         bufp += sizeof(struct elf_phdr);
 351         offset += sizeof(struct elf_phdr);
 352         nhdr->p_type    = PT_NOTE;
 353         nhdr->p_offset  = 0;
 354         nhdr->p_vaddr   = 0;
 355         nhdr->p_paddr   = 0;
 356         nhdr->p_filesz  = 0;
 357         nhdr->p_memsz   = 0;
 358         nhdr->p_flags   = 0;
 359         nhdr->p_align   = 0;
 360
 361         /* setup ELF PT_LOAD program header for every area */
 362         list_for_each_entry(m, &kclist_head, list) {
 363                 phdr = (struct elf_phdr *) bufp;
 364                 bufp += sizeof(struct elf_phdr);
 365                 offset += sizeof(struct elf_phdr);
 366
 367                 phdr->p_type    = PT_LOAD;
 368                 phdr->p_flags   = PF_R|PF_W|PF_X;
 369                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
 370                 phdr->p_vaddr   = (size_t)m->addr;
 371                 phdr->p_paddr   = 0;
 372                 phdr->p_filesz  = phdr->p_memsz = m->size;
 373                 phdr->p_align   = PAGE_SIZE;
 374         }
 375
 376         /*
 377          * Set up the notes in similar form to SVR4 core dumps made
 378          * with info from their /proc.
 379          */
 380         nhdr->p_offset  = offset;
 381
 382         /* set up the process status */
 383         notes[0].name = CORE_STR;
 384         notes[0].type = NT_PRSTATUS;
 385         notes[0].datasz = sizeof(struct elf_prstatus);
 386         notes[0].data = &prstatus;
 387
 388         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 389
 390         nhdr->p_filesz  = notesize(&notes[0]);
 391         bufp = storenote(&notes[0], bufp);
 392
 393         /* set up the process info */
 394         notes[1].name   = CORE_STR;
 395         notes[1].type   = NT_PRPSINFO;
 396         notes[1].datasz = sizeof(struct elf_prpsinfo);
 397         notes[1].data   = &prpsinfo;
 398
 399         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 400         prpsinfo.pr_state       = 0;
 401         prpsinfo.pr_sname       = 'R';
 402         prpsinfo.pr_zomb        = 0;
 403
 404         strcpy(prpsinfo.pr_fname, "vmlinux");
 405         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 406
 407         nhdr->p_filesz  += notesize(&notes[1]);
 408         bufp = storenote(&notes[1], bufp);
 409
 410         /* set up the task structure */
 411         notes[2].name   = CORE_STR;
 412         notes[2].type   = NT_TASKSTRUCT;
 413         notes[2].datasz = sizeof(struct task_struct);
 414         notes[2].data   = current;
 415
 416         nhdr->p_filesz  += notesize(&notes[2]);
 417         bufp = storenote(&notes[2], bufp);
 418
 419 } /* end elf_kcore_store_hdr() */
 420
 421 /*****************************************************************************/
 422 /*
 423  * read from the ELF header and then kernel memory
 424  */
 425 static ssize_t
 426 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 427 {
 428         ssize_t acc = 0;
 429         size_t size, tsz;
 430         size_t elf_buflen;
 431         int nphdr;
 432         unsigned long start;
 433
 434         read_lock(&kclist_lock);
 435         size = get_kcore_size(&nphdr, &elf_buflen);
 436
 437         if (buflen == 0 || *fpos >= size) {
 438                 read_unlock(&kclist_lock);
 439                 return 0;
 440         }
 441
 442         /* trim buflen to not go beyond EOF */
 443         if (buflen > size - *fpos)
 444                 buflen = size - *fpos;
 445
 446         /* construct an ELF core header if we'll need some of it */
 447         if (*fpos < elf_buflen) {
 448                 char * elf_buf;
 449
 450                 tsz = elf_buflen - *fpos;
 451                 if (buflen < tsz)
 452                         tsz = buflen;
 453                 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
 454                 if (!elf_buf) {
 455                         read_unlock(&kclist_lock);
 456                         return -ENOMEM;
 457                 }
 458                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
 459                 read_unlock(&kclist_lock);
 460                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 461                         kfree(elf_buf);
 462                         return -EFAULT;
 463                 }
 464                 kfree(elf_buf);
 465                 buflen -= tsz;
 466                 *fpos += tsz;
 467                 buffer += tsz;
 468                 acc += tsz;
 469
 470                 /* leave now if filled buffer already */
 471                 if (buflen == 0)
 472                         return acc;
 473         } else
 474                 read_unlock(&kclist_lock);
 475
 476         /*
 477          * Check to see if our file offset matches with any of
 478          * the addresses in the elf_phdr on our list.
 479          */
 480         start = kc_offset_to_vaddr(*fpos - elf_buflen);
 481         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 482                 tsz = buflen;
 483
 484         while (buflen) {
 485                 struct kcore_list *m;
 486
 487                 read_lock(&kclist_lock);
 488                 list_for_each_entry(m, &kclist_head, list) {
 489                         if (start >= m->addr && start < (m->addr+m->size))
 490                                 break;
 491                 }
 492                 read_unlock(&kclist_lock);
 493
 494                 if (&m->list == &kclist_head) {
 495                         if (clear_user(buffer, tsz))
 496                                 return -EFAULT;
 497                 } else if (is_vmalloc_or_module_addr((void *)start)) {
 498                         char * elf_buf;
 499
 500                         elf_buf = kzalloc(tsz, GFP_KERNEL);
 501                         if (!elf_buf)
 502                                 return -ENOMEM;
 503                         vread(elf_buf, (char *)start, tsz);
 504                         /* we have to zero-fill user buffer even if no read */
 505                         if (copy_to_user(buffer, elf_buf, tsz)) {
 506                                 kfree(elf_buf);
 507                                 return -EFAULT;
 508                         }
 509                         kfree(elf_buf);
 510                 } else {
 511                         if (kern_addr_valid(start)) {
 512                                 unsigned long n;
 513
 514                                 n = copy_to_user(buffer, (char *)start, tsz);
 515                                 /*
 516                                  * We cannot distingush between fault on source
 517                                  * and fault on destination. When this happens
 518                                  * we clear too and hope it will trigger the
 519                                  * EFAULT again.
 520                                  */
 521                                 if (n) {
 522                                         if (clear_user(buffer + tsz - n,
 523                                                                 n))
 524                                                 return -EFAULT;
 525                                 }
 526                         } else {
 527                                 if (clear_user(buffer, tsz))
 528                                         return -EFAULT;
 529                         }
 530                 }
 531                 buflen -= tsz;
 532                 *fpos += tsz;
 533                 buffer += tsz;
 534                 acc += tsz;
 535                 start += tsz;
 536                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 537         }
 538
 539         return acc;
 540 }
 541
 542
 543 static int open_kcore(struct inode *inode, struct file *filp)
 544 {
 545         if (!capable(CAP_SYS_RAWIO))
 546                 return -EPERM;
 547         if (kcore_need_update)
 548                 kcore_update_ram();
 549         if (i_size_read(inode) != proc_root_kcore->size) {
 550                 mutex_lock(&inode->i_mutex);
 551                 i_size_write(inode, proc_root_kcore->size);
 552                 mutex_unlock(&inode->i_mutex);
 553         }
 554         return 0;
 555 }
 556
 557
 558 static const struct file_operations proc_kcore_operations = {
 559         .read           = read_kcore,
 560         .open           = open_kcore,
 561         .llseek         = generic_file_llseek,
 562 };
 563
 564 #ifdef CONFIG_MEMORY_HOTPLUG
 565 /* just remember that we have to update kcore */
 566 static int __meminit kcore_callback(struct notifier_block *self,
 567                                     unsigned long action, void *arg)
 568 {
 569         switch (action) {
 570         case MEM_ONLINE:
 571         case MEM_OFFLINE:
 572                 write_lock(&kclist_lock);
 573                 kcore_need_update = 1;
 574                 write_unlock(&kclist_lock);
 575         }
 576         return NOTIFY_OK;
 577 }
 578 #endif
 579
 580
 581 static struct kcore_list kcore_vmalloc;
 582
 583 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
 584 static struct kcore_list kcore_text;
 585 /*
 586  * If defined, special segment is used for mapping kernel text instead of
 587  * direct-map area. We need to create special TEXT section.
 588  */
 589 static void __init proc_kcore_text_init(void)
 590 {
 591         kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
 592 }
 593 #else
 594 static void __init proc_kcore_text_init(void)
 595 {
 596 }
 597 #endif
 598
 599 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
 600 /*
 601  * MODULES_VADDR has no intersection with VMALLOC_ADDR.
 602  */
 603 struct kcore_list kcore_modules;
 604 static void __init add_modules_range(void)
 605 {
 606         kclist_add(&kcore_modules, (void *)MODULES_VADDR,
 607                         MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
 608 }
 609 #else
 610 static void __init add_modules_range(void)
 611 {
 612 }
 613 #endif
 614
 615 static int __init proc_kcore_init(void)
 616 {
 617         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
 618                                       &proc_kcore_operations);
 619         if (!proc_root_kcore) {
 620                 printk(KERN_ERR "couldn't create /proc/kcore\n");
 621                 return 0; /* Always returns 0. */
 622         }
 623         /* Store text area if it's special */
 624         proc_kcore_text_init();
 625         /* Store vmalloc area */
 626         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 627                 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 628         add_modules_range();
 629         /* Store direct-map area from physical memory map */
 630         kcore_update_ram();
 631         hotplug_memory_notifier(kcore_callback, 0);
 632
 633         return 0;
 634 }
 635 module_init(proc_kcore_init);